An Introduction to Nutrition

Nutrition in Your Life Nutrition The science of foods and the substances they contain Nutrients Include most biomolecules, vitamins, and minerals Required for synthesis of new molecules Required for energy for maintenance, growth, and repair Obtained through food Water is considered a nutrient Levels regulated during and following meals

Categories of nutrients Macronutrients Must be consumed in relatively large quantities Needed in daily amounts All are organic molecules Micronutrients Must be consumed in relatively small quantities Vitamins and minerals Essential Must be obtain and absorbed via digestive system from diet Nonessential Provided by biochemical processes of body Not required in diet

Nutrition in Your Life Food Derived from plant or animal sources Provide energy and nutrients Used by the body for maintenance, growth, and repair

Nutrition in Your Life Diet The foods one consumes The quality of which affects the risk of chronic diseases

Food Choices Personal preference Habit Ethnic heritage or tradition Social interactions Availability, convenience, economy

Food Choices Positive and negative associations Emotional comfort Recommended daily allowance (RDA) Amount of each nutrient that must be obtained each day Established values for nutrients set by federal agencies Originally established by Food and Nutrition Board Reviewed and updated periodically Used for food planning, food labeling, education, etc. In the future your RDA could be based on your genetic makeup Positive and negative associations Emotional comfort Values Body weight and image

Food Choices Nutrition and health benefits Functional foods Provide health benefits beyond their nutrient contributions Ex. Whole foods, fortified foods

The Nutrients Energy defined Nutrient defined

The Nutrients Composition of foods Six classes of nutrients Nonnutrients

Body Composition

Carbohydrates Structurally classified as Monosaccharides Disaccharides Polysaccharides When describing dietary sources, classified as Sugars Starch Fiber

Carbohydrates Sugars Include monosaccharides Glucose Fructose Galactose Include disaccharides Sucrose (e.g., table sugar, syrup, fruits) Lactose (e.g., milk sugar) Maltose (e.g. found in cereals) Other sugars Dextrose, brown sugar, honey, molasses, etc. Starch Polysaccharide polymer of glucose molecules found in certain foods E.g., tubers, grains, beans and peas Refined starches sometimes added as thickeners, stabilizers E.g., cornstarch Fiber Includes fibrous molecules of both plants and animals Cannot be chemically digested and absorbed by GI tract Sources Lentils, peas, beans, whole grains, oatmeal, berries, nuts

The Nutrients Chemical composition of nutrients Inorganic vs. Organic nutrients

The Nutrients Inorganic nutrients Minerals Water

The Nutrients Organic nutrients Carbohydrates Lipids Proteins Vitamins

The Nutrients Essential nutrients Macronutrients vs. micronutrients

Energy-Yielding Nutrients Energy from foods Energy density

Energy Density

Energy-Yielding Nutrients Energy in the body Energy for activity Stored energy Other roles of energy-yielding nutrients

Vitamins Organic Not energy-yielding Essential Water-soluble vs. fat-soluble Vulnerable to destruction

Minerals Inorganic Not energy-yielding Essential Indestructible

Vitamins Vitamins Fat-soluble vitamins Organic molecules required for normal metabolism Present in only small amounts in food Water-soluble or fat-soluble Essential or nonessential Water-soluble vitamins Dissolve in water B vitamins and vitamin C Easily absorbed into blood from digestive tract Excess excreted in urine Some coenzymes assist with normal enzyme function Fat-soluble vitamins Dissolve in fat Vitamins A, D, E, and K Absorbed from GI tract within micelles Excess stored in fat May become toxic if taken in excess Functions Vitamin A, precursor of visual pigment retinal Vitamin D, forms calcitriol, increases calcium absorption from GI tract Vitamin E, stabilizes and prevents damage to cell membranes Vitamin K, required for synthesis of blood clotting proteins

Water Inorganic Not energy-yielding Essential

The Science of Nutrition Human genome Nutritional genomics

Nutrition Research The Scientific Method Hypothesis vs. Theory Experimental group vs. control group Randomization Sample size

Dietary Reference Intakes Estimated Average Requirements Recommended Dietary Allowances Adequate Intakes Tolerable Upper Limits

DRI

Energy Recommendations Estimated Energy Requirement Acceptable Macronutrient Distribution Ranges Carbohydrate: 45% - 65% Fat: 20% - 35% Protein: 10% - 35%

Energy Recommendations

Using Nutrient Recommendations Estimates of energy & nutrient intakes apply to healthy people Recommendations are NOT minimum requirements Recommendations are NOT optimal for all people Recommendations should be met by consuming a varied diet Recommendations apply to average daily intakes

Nutrition Assessment Malnutrition Undernutrition vs. overnutrition

Diet and Health

Nutrition Information and Misinformation Not everything on the Internet is true!! Determination of the reliability of a website Not everything on the news is accurately reported!!

Nutrition Information and Misinformation American Dietetic Association (ADA) Registered dietitian (RD) Dietetic technician, registered (DTR)

Nutrition Information and Misinformation Finding credible information Professional health organizations Professional journals